1. Field of the Invention
The present invention relates to a perpendicular magnetic recording head which performs a recording action by applying a recording magnetic field perpendicularly to a recording medium plane.
2. Related Background Art
As is well-known, a perpendicular magnetic recording head includes a main magnetic pole layer and a return yoke layer which are laminated with a magnetic gap layer interposed therebetween on a surface opposing a recording medium (medium-opposing surface) and are magnetically coupled to each other on the rear side of the medium-opposing surface in the height direction, and a coil layer which is provided between the main magnetic pole layer and return yoke layer on the rear side of the medium-opposing surface in the height direction and generates a recording magnetic flux upon energization. The recording magnetic flux generated from the coil layer perpendicularly enters a hard magnetic film of the recording medium from the front end face of the main magnetic pole layer exposed at the medium-opposing surface and returns to the front end face of the return yoke layer exposed at the medium-opposing surface through a soft magnetic film of the recording medium. This performs magnetic recording at a part opposing the front end face of the main magnetic pole layer.
Known in such a perpendicular magnetic recording head is a structure equipped with a yoke layer having a large capacity formed on the upper or lower side of the main magnetic pole layer in order to augment the amount of magnetic fluxes accommodated in the main magnetic pole layer (Patent Document (Japanese Patent Application Laid-Open No. 2006-221785)). In this structure, magnetic fluxes generated from the coil layer at the time of a recording action are guided to the main magnetic pole layer through the yoke layer, so that the amount of magnetic fluxes released from the front end face of the magnetic pole layer exposed at the medium-opposing surface increases, whereby the recording magnetic field intensity can be enhanced.
When the recording magnetic field intensity is higher, however, the remanent magnetization in the main magnetic pole layer after the completion of the recording action also increases, whereby unintentional writing (pole lockup phenomenon) may be effected on the recording medium by magnetic fluxes leaking from the front end face of the main magnetic pole layer at the time of no recording action (when the coil layer is not energized). For preventing this phenomenon from occurring, it is necessary to define the domain structure of the main magnetic pole layer for stabilizing the magnetization in a direction orthogonal to the direction of the magnetic flux perpendicularly incident on the recording medium, i.e., track width direction, such that unnecessary magnetic fluxes are harder to leak at the time of no recording action. Examples of such a domain structure of the main magnetic pole layer are described in Patent Documents (Japanese Patent Application Laid-Open No. 2006-221785, Japanese Patent Application Laid-Open No. 05-166130, Japanese Patent Application Laid-Open No. 2000-331310, Japanese Patent Application Laid-Open No. 2006-147058).